"The liver demonstrates mild diffuse increased echogenicity, most consistent with fatty liver infiltration or fibrosis." What does this mean?

Distinguish diseases. Distinguish fatty liver (steatosis) from fatty liver with abnormal liver tests (steatohepatitis). Best to start with a weight loss diet based on calorie and fat restriction, avoid alcohol, control diabetes & cholesterol (if present). Your doctor will likely want to monitor your labwork, image the liver, & rule out other diseases that can mimick the pattern of liver tests seen with fatty changes.